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09-12-2009, 07:02 AM   #1
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K20D and external flash advice

I have had my K20D for a few months now and am still getting used to the many features. I have just bought a Metz 48AF-1 flash as research suggested it is a good alternative to the Pentax 360 and is more within my budget.

It can be set in 2 modes, M-manual or P-TTL. As I understand it if I use M mode the flash fires at full output and I have to control the exposure with the camera. P-TTL takes information from the camera and sets the flash accordingly.

I have a few questions:

1. Do I have to change the camera flash settings in the fn menu to transfer this to the flash or are they all disabled when using an external flash?

2. With P-TTL I am finding the pictures tend to be under exposed. No doubt this is my error and not the equipment. As a guide, what would be the best setting to have the camera on and what am I likely to be doing wrong? I know this is a vague statement but perhaps I could be pointed in the right directiion.

3. If I leave the camera settings alone after taking an under exposed shot and then change the flash to manual it seems easier to get the right exposure but this seems to defeat the idea of fully automatic, which is what I bought this for.

I know it will come with experience but I would appreciate some advice on using this type of flash.

Many thanks.


Last edited by Misty; 09-12-2009 at 08:33 AM.
09-12-2009, 07:27 AM   #2
Ash
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Hi Misty.
I don't have the Metz 48 to know specifics, but I know that in P-TTL, the Fn menu flash settings still apply, including the FEC, which alters flash output accordingly.

P-TTL has been criticised for being inconsistent and causing under-exposed flash photos. I've not had this experience as long as I've set the FEC at +0.7, which gives me good flash results everytime, whether bounced or direct. It's all a matter of knowing your gear well, and not blaming it until you've gotten accustomed to its nuances.

Manual mode should have the option of 1/1 (full) power as well as half increments down to something like 1/16 or 1/32. See if you can alter this setting on your flash - that way you definitely get consistent flash output at the intensity you want, not just full power.

Hope this helps.
09-12-2009, 08:42 AM   #3
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Hello Ash,
Thanks for the advice re FEC. I can change this on the flash for +/ - to 3.0 and noticed this helps. It can also be altered on the camera. When you said you have set your FEC do you mean on the flashgun or within the camera settings or both. I was unsure whether changing the cameras settings in the flash menu would have any effect on the external one. If I have understood you right it seems I can control the output from the camera such as red eye, slow speed sync etc and this will alter the external flash to correspond.

If I set the cameras flash FEC as you suggest that should help with the 48 AF-1 exposure??
09-13-2009, 11:31 AM   #4
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I believe as long as you are in P-TTL mode you can adjust the flash output from the camera menu..

12-14-2009, 09:36 AM   #5
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This is the exact thing i'm trying to wrap my brain around.

If you have conflicting settings between the external flash and the in-camera settings, which one "wins"?

I generally just leave the in-camera settings on the flash icon and control everything from the external flash. Is this acceptable?
12-14-2009, 01:04 PM   #6
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They both apply.
So you can conceivably increase FEC by a total of a whopping +4! +1 on the camera's FEC setting, +1 on the external flash FEC setting, then +2 on the camera's EV compensation setting, which also seems to increase flash output when coupled with a P-TTL flash.

Now, all this is of course limited to the flash's power rating (guide number), but I'm not sure anyone would want anywhere near 4 stops more light than the camera's calculated amount for any scene...
12-16-2009, 02:30 PM   #7
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I have a Metz 48 for my K200D for all of 3 weeks, and I can confirm:
- in P-TTL mode messing with the camera's flash functions does affect the flash output. A handy related function is the camera's exposure bracketing (not the flash's): you'll get 3 pix all with different flash outputs. The flash has this function too, but it cancels after each set of 3 pix and must be reset.
- in Manual mode, you can dial down the power just by hitting the "-" button, down to 1/128th of full power. This is easy way to find the right power, though you may waste a shot or two getting there.

Craig
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